The present invention relates to an electrical device including a plurality of apparatus and a method of setting an address of each of the apparatus. More specifically, the present invention relates to an electrical device including a plurality of apparatus connected with a daisy chain connection through a communication line, and a method of setting an address of each of the apparatus.
A conventional electrical device includes a plurality of conventional apparatus connected with a daisy chain connection through a communication line. There have been proposed several conventional methods for setting an address of each of the conventional apparatus of the convention electrical device.
For example, in the conventional method disclosed in Patent References 1 to 3, when an address is set to each of the conventional apparatus connected with the daisy chain connection, it is configured such that an address number received thereto or an address number with a specific value added thereto is set as an address number of the conventional apparatus its self. Then, a specific value is added to the address number thus received to generate a new address number, so that the new address number is transmitted to a conventional apparatus at a later stage.    Patent Reference 1: Japanese Patent Publication No. 05-101004    Patent Reference 2: Japanese Patent Publication No. 07-105121    Patent Reference 3: Japanese Patent Publication No. 2001-31028
In the conventional electric device and the conventional method of setting an address, there are the following problems. Firstly, in setting a new address, when the new address number is generated in the conventional apparatus and transmitted to the conventional apparatus at the later stage, there has been known a conventional technique, in which data for checking reliability such as CRC (Cyclic Redundancy Check) and the like is generated. Then, the data are added to the newly generated address number, so that reliability of the address number can be checked in the conventional apparatus at the later stage. In the convention technique described above, however, it is necessary to generate the data for checking reliability every time when the address number is generated. Accordingly, it is necessary to take a long period of time for setting the addresses of the conventional apparatus in the convention electric device.
Secondly, in order to shorten the period of time for generating the data for checking reliability, there has been a technique, in which the data for checking reliability are assigned to the address numbers most likely generated, so that the data for checking reliability are prepared as table data. In the convention technique described above, however, an amount of the data for checking reliability to be prepared tends to increase as the number of the conventional apparatus whose addresses to be set increases. Accordingly, it is necessary to install a large capacity memory in the conventional electric device upon manufacturing, or to design the convention electric device capable of connecting a wide range number of the conventional apparatus. In this case, the number of the data for checking reliability, which can be stored in the electric device, is dependent on the memory capacity. As a result, the number of the conventional apparatus capable of being connected to the conventional electric device is restricted with the memory capacity.
In view of the problems described above, an object of the present invention is to provide an electrical device and a method of setting an address capable of solving the problems of the conventional electrical device. In the electrical device and the method of setting an address of the present invention, it is possible to alleviate the restriction in the number of the apparatus capable of being disposed in the electric device while preventing the period of time for setting the address from increasing.
Further objects and advantages of the invention will be apparent from the following description of the invention.